Paleozoic Era, one of the major divisions of geologic time. It began 570,000,000 years ago and ended 240,000,000 years ago. During the era, plant and animal life evolved in the sea and invaded the land.
| Paleozoic Era | |||
| Period | Began | Lasted | Animal life |
| Cambrian | 543 million years ago | 53 million years | Trilobites were common in the sea. Jawless fish appeared. Land was bare. |
| Ordovician | 505 million years ago | 65 million years | Mollusks and coral were plentiful in the sea. Algae became common. |
| Silurian | 440 million years ago | 30 million years | Fish developed jaws. Plants appeared on land. |
| Devonian | 410 million years ago | 50 million years | Fish were plentiful. Insects and amphibians appeared. |
| Carboniferous | 360 million years ago | 70 million years | Crustaceans, fish, and amphibians were plentiful. Reptiles appeared. Huge, swampy forests grew. Giant insects lived in the forests. |
| Permian | 290 million years ago | 39 million years | Seed plants appeared. Trilobites died out near the period's end. |
